I can't browse through the my submenues while holding BT3 (right mouse)
down with freeglut sources.
I have enabled BT3-release as additional menue trigger, which using
glut.org sources instead works fine, even with several levels of submenues .
Using glut.org the submenues open and close while moving around the
mouse holding BT3 down and I can select any item by simply releasing the
one-and-only button I used to start the menue system.
The problem is, that all the SUBmenues do NOT open until I release BT3,
and than I have to use BT1 to do a selection.